1. Field of the Invention
The present invention relates to a dielectric ceramic composition and to a ceramic electronic element using the same, particularly to a dielectric ceramic composition which is used as a material for a dielectric used in microwave resonators, filters, laminated capacitors, and other applications, or to a ceramic material for multilayer circuit boards and to a ceramic electronic element using the same.
2. Description of the Related Art
Conventionally, efforts have been made to replace cavity resonators with ceramic dielectrics having a high dielectric constant in order to miniaturize electronic apparatus such as microwave resonators and microwave filters. Briefly, the resonators and the filters are miniaturized by use of an effect that the wavelength of an electromagnetic wave in a dielectric is shortened to 1/.epsilon..sup.1/2 times that in free space, wherein .epsilon. represents the dielectric constant of the dielectric.
However, since the relative dielectric constant .epsilon. of a ceramic dielectric material having a temperature coefficient suitable for use as a dielectric resonator has so far been limited to 100 or less, the dielectric material has not met the recent demand for further miniaturization.
A method employing an LC resonator which has conventionally been known in connection with microwave circuits is effective for meeting the demand under restriction of relative dielectric constant .epsilon. of a ceramic dielectric material. Thus, a further miniaturized electronic apparatus having high reliability may be produced by application to fabrication of LC circuits of a lamination method which is adapted in practice for laminated capacitors and multilayer boards.
However, use of a lamination method to produce an LC resonator having a high Q value in a microwave region requires high electric conductivity of the internal electrode which is built into a laminated capacitor and a multilayer circuit board. Briefly, a metal material having high electric conductivity such as gold, silver or copper must be used for an internal electrode which is fired simultaneously with a dielectric or a multilayer circuit board. For this reason, the dielectric material must be a low-temperature-sinterable material which is able to be sintered simultaneously with internal electrodes formed of a metal material having a low melting point, and as well must have a high dielectric constant, a high Q value and a high degree of temperature stability. However, a dielectric material which meets all of these criteria has not yet been found.